How can I get IOBluetoothDevice's battery level, using Swift and AppKit (Xcode for MacOS)

Question

I am using Xcode to develop a MacOS app, based on Cocoa & AppKit, written in Swift.

I am using IOBluetoothDevice objects throughout my app, and I want to be able to display the devices' battery levels, if accessible.

I expect that devices which battery levels are visible on the OS's Bluetooth settings (see image below), to be also accessible programmatically (e.g., AirPods, Magic Keyboard, etc.). However, I could not find this anywhere.

I have also thought about executing a terminal command and found this thread, but it did also not work.

Thanks

Answer 1

You can get the battery level of Bluetooth devices from the IORegistry with IOKit.

This is a simple example to get the battery level for the Magic Trackpad 2

import IOKit

var serialPortIterator = io_iterator_t()
var object : io_object_t
let port: mach_port_t
if #available(macOS 12.0, *) {
    port = kIOMainPortDefault // New name in macOS 12 and higher
} else {
    port = kIOMasterPortDefault // Old name in macOS 11 and lower
}
let matchingDict : CFDictionary = IOServiceMatching("AppleDeviceManagementHIDEventService")
let kernResult = IOServiceGetMatchingServices(port, matchingDict, &serialPortIterator)

if KERN_SUCCESS == kernResult {
    repeat {
        object = IOIteratorNext(serialPortIterator)
        if object != 0, let percent = IORegistryEntryCreateCFProperty(object, "BatteryPercent" as CFString, kCFAllocatorDefault, 0).takeRetainedValue() as? Int {
            print(percent)
            break
        }
    } while object != 0
    IOObjectRelease(object)
}    
IOObjectRelease(serialPortIterator)

For other devices you have to replace AppleDeviceManagementHIDEventService and Trackpad2 with the appropriate values. You can display the entire IORegistry in Terminal.app with ioreg -l.